1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable.
Here, the electrophotographic image forming apparatus is an apparatus which forms an image on a recording material using an electrophotographic image-formation type formation type method. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (a laser beam printer, an LED printer or the like), a facsimile machine and a word processor.
The process cartridge is a cartridge which contains, as a unit, an electrophotographic photosensitive drum, and process means, such as charging means for electrically charging the electrophotographic photosensitive drum, developing means and the like, and which is detachably mountable to a main assembly of the image forming apparatus.
Such a process cartridge is mounted to and demounted from the main assembly of the image forming apparatus by the user, and therefore, the maintenance operations for the main assembly of the apparatus are carried out in effect by replacing the process cartridge.
2. Description of Related Art
As disclosed in Japanese Laid-open Patent Application 2003-215876, a conventional electrophotographic image forming apparatus has mounting portions to which a plurality of the detachably mountable process cartridges are arranged in the vertical direction, wherein the mounting portions are independent from each other. A spacer member (spacing plate) for spacing and contacting the developing roller relative to the photosensitive drum is placed at a position of reduced influence on to the mounting of the process cartridge.
On the other hand, as disclosed in Japanese Laid-open Patent Application Hei 5-173375, in an electrophotographic image forming apparatus wherein the process cartridge is detachably mountable substantially in the horizontal direction, the process cartridge can be integrally drawn out, thus making the process cartridge mounting and demounting operations easy.
In such a structure, the arrangement of the spacing member for spacing or contacting the developing roller relative to the photosensitive drum has been difficult.